Wood pulp and method of producing same



Patented Dec. 30, 1 952 2,623,875 WOOD PULP AND METHOD OF PRODUCING SAMEPaul Henry Schlosser and Kenneth Russell Gray,

Shelton, Wash., assignors to Rayonier Incorporated, Shelton, Wash., acorporation of Delaware No Drawing.

Application September 9, 1950,

Serial No. 184,108

4 Claims. (Cl. 260-212) This invention relates to the production ofcellulosic products and has for its general object the provision ofcertain improvements in carrying out one or more of the processing stepsused in the production of such products. The invention aims particularlyto minimize inactivation effects in the production of a substantiallydry sheet of refined wood pulp from a slurry of wet fibers. Theinvention further contemplates, as a new article of manufacture,substantially dry refined wood pulp in sheet form having incorporatedtherein a mixed ether containing a polyethylene oxide radical and analiphatic hydrocarbon radical containing more than 7 carbon atoms.

In one of its important aspects, the invention involves the use ofsubstantially dry refined wood pulp as a source of cellulose in thepreparation of cellulosic derivatives, and has for a particular objectincorporating mixed ethers in the pulp prior to completion of drying atan elevated temperature, whereby inactivation of the pulp as regardsproduction of cellulosic derivatives is greatly minimized.

As used in this specification substantially dry refers to pulp eitherdried bone dry or containing that small moisture content which pulpbeing a hydroscopic substance would take up from the air. Roughly thiswill refer to pulp containing from zero to ten percent moisture.

In the preparation of refined wood pulp, the purified fibers are firstobtained in the form of a slurry in water. In this undried state, therefined wood pulp fibers are extremely reactive. This is evidenced bythe fact that in conversion processes taking place in non-aqueous media,such as in the production of cellulose acetate, if the water associatedwith the wet fibers is first displaced by organic solvents, the fibersare very reactive. place in an aqueous medium, such as the conversion tocellulose xanthate in the viscose process, the wet fibers may be veryreadily converted by treatment in slurry form without drying.

For practical reasons, however, it is generally necessary to form thepulp fibers into a dry pulp sheet, using heat to remove practically allthe water. In such dry sheet form, the pulp may be readily shipped todistant factories for conversion into various derivatives. Also, in suchrelatively dry form, the pulp may be used in nonaqueous conversionprocesses without the need for expensive displacement of water byorganic solvents.

However, in the formation of the pulp sheet Again in conversionprocesses taking and the drying at elevated temperature, the pulp fibersundergo various degrees of inactivation.

As regards use in the cellulose acetate process, such inactivationeffects probably result largely from the drying at elevated temperature.

As regards use in conversion processes taking place in aqueous media, wefind that inactivation is due in large part to mechanical effects ofsheet formation. Such type of inactivity may be due to mechanicalcompacting which makes it difficult in subsequent processing tocompletely comminute the sheet without excessive damage to the fibers.We further find that such inactivity of dry pulp in sheet form towardaqueous processing is not particularly a function of the dryingtemperature but rather results from the substantial removal in pulppurification of the impurities removable by organic solvents, as forexample, by ether, benzene, alcohol, etc. These impurities, oftenloosely called resins, are mainly of the natureof waxes, fats and trueresins, the latter often being present in a relatively small amount.

One of the main objects in the manufacture of a highly refined pulp forthe viscose process is to remove as much as possible of thenoncellulosic impurities, so that a whiter, purer pulp results, which iscapable, in the manufacture of rayon, of producing a higher grade yarn.

We find, however, that not all of the noncellulosic impurities which canbe removed are undesirable, and in fact, certain of such impurities,normally present in small amounts, are highly beneficial in minimizinginactivity in the dry pulp sheet as regards processing the pulp intoderivatives in aqueous solution. These impurities are particularlybeneficial in promoting reactivity in the viscose process, especially asregards producing a reactive shredded alkali cellulose. The beneficialimpurities which aid the shredding operation are probably of the natureof fiber lubricants which permit the steeped and pressed pulp sheets tobe thoroughly shredded into a fluffy condition more readily and withoutmechanical damage to the alkali cellulose fibers, which would cause themto react incompletely with carbon bisulfide.

Pulp sheets which may tend to be unreactive toward processing intoderivatives in aqueous solution will in general be characterized byhaving an ether extract of not more than about 0.15% where such valuesrefer to the amount of natural ether-extractable material left in the P-P after the purification process. Such unre-.-

activity will tend to increase as the residual ether extract approacheszero.

We have discovered certain compounds, not normally present in pulp,which when added to the pulp in minute quantities prior to completion ofdrying, greatly minimize inactivation effects in the production of a drypulp sheet from the wet fiber slurry. The compounds of our inventionminimize both that inactivity primarily due to heat, as regards use incellulose acetate preparation, and that inactivity due to sheetformation in pulp of low ether extract, as regards use in aqueousconversion processes (e. g, formation of a reactive alkali cellulose inthe viscose or cellulose ether processes).

In accordance with the invention a small quantity of a mixed ethercontaining a polyethylene oxide radical and an aliphatic hydrocarbonradical containing more than '7 carbon atoms is incorporated in thepulp. Inthe preferred. form of the invention the compounds areincorporated in the pulp prior to completion of drying the pulp at anelevated temperature on the sheet forming machine.

For minimizing inactivity in the acetylation and other esterificationprocesses carried out in non-aqueous solution, for satisfactory benefitit is necessary that at least the surfaces of the sheet be completelytreated prior to final drying at elevated temperature. For use in theviscose process (or in other aqueous processes in which a shreddedalkali cellulose is produced at an intermediate step) while the samemanner of application is very satisfactory, nevertheless, substantialimprovements may also be obtained by treating only portions of the sheetand even by application after drying on the machine is completed.

The compounds which we discovered for use in the invention are veryeffective in preventing loss of reactivity of the fibers during theformation of the dry pulp sheet and accordingly can be used in verysmall quantities.

The treated pulp of our invention containing the mixed ethers may beused with particular advantages in the The treated pulp, however, may beused forv the production of other cellulose derivatives such ascellulose xanthate in the viscose process.

For convenient application in our invention the mixed ethers arepreferably substantially soluble in water, Such compounds will generallycontain a polyethylene oxide radical, having at least half as manyethenoxy groups as there are carbon atoms in the hydrocarbon radical.Practica'lly, it is believed there is no upper limit for the number ofethenoxy groups in the polyethyl ene oxide radical. We have successfullyused materials with a polyethylene oxide group containing up to 157ethenoxy groups.

While the mixed ethers used in our invention are preferablysubstantially water soluble, it is possible however to use compounds ofonly slight solubility. Thus mixed ethers containing the simplestpossible polyethylene oxide radical composed of two ethenoxy groups, i.e. a diethylene glycol ether group, may be used. Even though suchproducts do not have a great solubility they still possess a sufiicienttendency tov emulsify so that they may be applied to the pulp in theform of an emulsion. If, however, a high degree of "solubility in wateris desired with such compounds, as for example, in the preparation ofconcentrated stock solutions for application to the pulp or in theviscose process, it may be advantageous to combine them with dispersingproduction of cellulose acetate.

2,623,875 Y I f oxide radical so that the products will be substantiallywater soluble without the aid of any additional dispersing agents.

Further, from the standpoint of eifectiveness the most preferred classof compounds are mixed ethers containing a polyethylene radical withfrom 8 to 50 ethenoxy groups and a normal primary aliphatic hydrocarbonradical with from 8 to 20 carbon atoms.

The mixed ethers used in the invention may be prepared by any of theknown methods for reacting ethylene oxide with a fatty alcohol. Thesemethods include warming the fatty alcohol with the appropriate quantityof ethylene oxide while employing a catalyst such as an alkali which maybe present either as a strong aqueous solu-' tion or as an alkali metalalcoholate. 'Again the mixed ethers maybe prepared by etherifying thefatty alcohols with polyethylene glycols, as for example, by reactingthe sodium salt of the fatty alcohol with a halogen hydrin of thepolyethylene glycol. I

We prefer, however, to react ethylene oxide at moderate temperatureswith aliphatic fatty alcohols containing more than 7 carbon atoms,incorporating an alkali as catalystwith the alcohol. Suitable methodsfor incorporation of the alkali include:

(1) Addition of a small amount of concentrated caustic soda to thealcohol, e. g., about 0.25 to 1.5% by weight of 48% caustic soda. Thisis an inexpensive method particularly suited to the preparation ofderivatives containing a relatively short polyethylene oxide chain.

(2) Dissolving metallic sodium in the molten fatty alcohol. We prefer touse about 0.1 to 4% of sodium by weight. I

(3) Addition of a solution of sodium in anhydrous liquid ammonia to asolution of the fatty alcohol in ether (or addition of liquid ammonia toan ether solution of the fatty alcohol followed by a subsequent additionof metallic sodium This method enables the preparation of sodium saltscontaining a theoretical amount of sodium. Since such salts contain muchmore sodium than can be introduced by method 2, they react much morerapidly with the ethylene oxide. 1

A convenient laboratory method for prepara tion of small quantities ofthe compounds follows: After incorporating alkali by one of the threemethods described above, the fatty alcohol and the required amount ofethylene oxide are placed in an autoclave and heated with agitationuntil the pressure drops substantially to zero. When alkali has beenincorporated by the first two methods and when using at least nine molsof ethylene oxide per mol of alcohol, a temperature of Bil-100 C. isusually a suitable reaction temperature. When using a theoretical sodiumsalt prepared by the third method or when incorporating alkali by any ofthe three methods and using less than nine mols of ethylene oxide, thereaction should be carried out at a considerably lower temperature, forexample 50-80 C.;

' may proceed too rapidly and surge to completion with explosiveviolence, resulting in a less pure product. After completion of thereaction, the residual alkali may be neutralized with 30 H2804 orconcentrated HCl.

1 oxide.

etfor the' preparation of the materials-on a large scale'the procedurewill be'similar to that out-1- lined except that it will usually bepreferable to introduce ethylene oxide in gaseous form at a relativelylow'. pressure from an external. container during the course of thereaction. In this way the possibility of uncontrolled reaction maybeavoided and, if desired, somewhat highe'r'reaction temperatures may beused.

For the purposes of our invention no subsequent purification will beusually required. Where an extremely-light-colored product is desired,however, thecompounds may be given subsequent treatment involvingdecolorizing with charcoal according to the methods well known to theart. A process used satisfactorily by us for both decolorizing theproducts and freeing them from inorganicsalt-consisted in dissolving theneutralized product. in benzene, decolorizing the benzene solution with'charcoal, drying the decolorized benzene solutioniby addition of sodiumsulphate and by evaporating off the benzene, finally applying vacuum.

.When the alkaline catalyst used consists of a small amount of 48%aqueous caustic soda all of the ethylene oxide will probably not beconsumed in extending the length ofthe polyether chain on the fattyalcohol, but a portion will be consumed with the formation ofpolyethylene v The presence of polyethyleneoxide is, however, notharmful to our invention, and is in fact in some cases even beneficial.

It is obvious that the fatty alcohols used for making the mixed ethersmay be prepared by any desired method; for example, synthetic fattyalcohols containing more than 7 carbon atoms and built up from smallermolecules may be used. Such compounds are usually essentially branchedchain molecules. We prefer, however, to use fatty alcohols prepared bycatalytic reduction by hydrogen of vegetable or animal oils according towell known practices, which are substantially straight chain compounds.It is, however, not necessary to use pure fatty alcohols. Indeed,

highermolecular weight alcohols prepared by hydrogeneration of fats andoils are generally, if notv always offered in commercial quantities inthe form of mixtures of different alcohols. Thus in place of pure laurylalcohol, technical lauryl alcohol may be used. essentially a mixture ofC10, C12, C14, C16 and C18, carbon length chains with the C12 chainpredominating. These mixtures of alcohols function in substantially theidentical manner as mixed tually, however, when using such a mixture inwhich lauryl alcohol predominates, the result is almost identical, as ifpure 'lauryl alcohol itself were used. Also, instead of using purestearyl alcohol it is satisfactory to use a technical mixture ofsaturated highermolecular weight fatty alcohols and in which stearylalcohol predominates. In place of ,pure oleyl alcohol, technical oleylalcohol as sold under the trade name of Ocenol may be used verysatisfactorily. In condensing such technical mixtures of fatty alcoholswith ethylene oxide, it is quite satisfactory to basethe desired molarratio of. ethylene oxide on the assumption that the entire weight offatty alcohol hasthe same molecular weight as the predominating fattyalcohol in the mixture. Thismay be done since small variations in theratio. of ethenoxy in the products do not produce very great;differences in the properties. Furthermore, even when using pure. fattyalcohols it is not nee- This is considered to be ethers of theindividual pure alcohols. Ac-

'e's'sary to use .e'xact stoichlometrical"proportions of ethylene oxide.Thus, for example,'if pure lauryl alcohol were treated with 12.5 mols ofethylene oxide, mixtures of mixed ethers would be obtained in whichchains of 12 and 13 ethenoxy groups would predominate.

Condensation products prepared by the meth ods described, and which havebeen used satisfactorily include: v

The mixed ethers may be incorporated in the W006. pulp at any stage inthe production of dry sheet pulp from the wet fiber slurry. For treatingthe pulp, the compounds may be incorporated either in the bulk pulpbefore sheet formation or in the sheet at any stage of the drying as byspraying the pulp with an aqueous solution or dispersion. A mostpractical and convenient method of securing the incorporation of themixed ethers prior to completion of drying is to incorporate the mixedether in the refined wood pulp while it is on the sheet forming machineby means of sprays or a rotating roll. Such application may be made tothe wet pulp web subsequent to removal of the mechanically removablewater by pressing, or later at any stage while it is passing through thehot dryer rolls prior to completion of drying.

When pulp is dried in a conventional manner on hot dryer rolls,inactivation of the fibers is greatest on the surface of the sheets.Thus, if desired, the treatment of the pulp sheet with the compounds maybe applied by spray or a rotating roll in such a manner that the mixedethers are largely incorporated near one or both surfaces of the sheet.Thus application is made largely to those fibers which would otherwisehave the greatest tendency toward inactivation. In any event there isproduced a substantially dry sheet of pulp containing a mixed etherincorporated prior to completion of drying.

While theinvention will be most usually applied in the drying of thepulp on the sheet forming machine as described above, it may also beapplied to the reactivation of the pulp fibers in a sheet which has beenalready dried at an elevated temperature. In such case the dried sheetpulp will have at least one or both surfaces treated with a watersolution of a mixed ether, as by spraying, or the dried pulp will becompletely treated by dipping. The sheet thus treated with a watersolution of a mixed ether will be r e-dried using such heat as may bepractically required. In such method of application it is believed thatthe reactivation is brought about at least in part by the rewetting ofthe sheet with the water and that one function of the mixed ethers is toprevent or minimize loss during the second drying of the improvedactivity obtained by the rewetting'operaion. Obviously,

however, where possible it-will be economically preferable to carry outthe treatment with the mixed ethers during the original drying on thesheet forming machine so that rewetting and redrying will beunnecessary.

The eifective proportion of the mixed ethers incorporated in the woodpulp during the production of dry pulp from a Wet slurry or in anyreactivation treatment is from 0.015 to 0.5% based on the weight of bonedry pulp. Above this range in general no additional advantages areobtained and there are disadvantages in that the pulp sheet will tend tobecome undesirably soft and dusty and will undesirably contaminate theend product from the pulp. The quantities which would be preferred inpractice for treating pulp intended for acetylation will, however,frequently be considerably less than 0.5% and will depend both on themethod of application and the economics. If essentially only thesurfaces of the sheet are treated, less compound will be required foreifecting a given amount of improvement than if the whole sheet istreated. This is because only those fibers would be treated which wouldhave the greatest tendency to become unreactive.

For pulp intended for viscose processing, it will generally be preferredto use somewhat lower quantities of compounds than that given as themaximum for pulp intended for acetylation. The preferred range for pulpintended for viscose use is from 0.015% to 0.2%. In general, quantitiesgreater than this will not be required for the purposes of the inventionand their use may give rise to certain disadvantages such as foaming inthe viscose and difficulty in obtaining completely ole-aerated viscosewhich is absolutely necessary for satisfactory spinning.

We find that sheet wood pulp dried in the presence of the mixed othershas markedly improved acetylation reactivity as compared with pulp driedin a conventional manner in the absence of these additives. This may bedemonstrated by the following convenient and rapid laboratory test forcomparing the aoetylation reactivity of samples of sheeted Wood pulpfibers:

Small specimens of the pulps to be examined are treated with a solutionof the mixed ether or With distilled water and dried in a circulatingoven at a selected controlled elevated temperature to dry them undercomparable conditions. An accurately Weighed sample of 0.5 gram of thispulp is torn into small bits and placed in a 35 ml. vial. A flattenedglass rod is placed in the vial through'a hole in the cap and the vialand sample set in a Water bath at 20 C. 1

The acetylating mixture is prepared by mixing 2.50 gms. H2804, 88.0 ml.acetic anhydride, and 175.0 ml. acetic acid. This mixture is unstableand should be freshly prepared every two days.

To the sample vial in the water bath 15 ml. of the acetylating mixtureare added from a pipette. The pulp and acid are mixed with the glassrod, which remains in the vial. The vials are stored in the water bathand the mixing repeated every 15-20 minutes. It is important to includea standard sample with each group of unknowns and to handle and agitateall samples alike.

As the pulp samples are acetylated by the mixture they dissolve to aclear solution. The time required for this solution to take place, therelative clarity and residual undissolved fibers, and the relativeappearance during the reaction time will indicate whether any of thesamples is more or less reactive than the standard.

TABLE I Acetylation reactivity of acetate wood pulps treated withpolyethenomy alkyl ethers Dis- Treated solving .Appear- Residual P 1111CB With time, ancc Fibers hrs.

water only 6.5 clear-.. Mauy,largc. A 5 None. B 5.5 Few, small C 5 doVeryiew small. Southern Pine". wateronly 6 "do Many, large.

Do C 5 do Few, small.

1 A-dodecaethenoxy ether oilaury] alcohol; B-nonadecaethenoxy other ofoleyl alcohol; C-Brij (commercially prepared polyethenoxy ether oflauryl alcohol) In the usual viscose process the sheets of wood pulp arefirst subjected to a steeping .step' to convert the cellulose to alkalicellulose-and the pressed sheets of alkali cellulose are then shreddedto form a fluffy mass of fibers. The fluffy mass is xantha'ted,dissolved in dilute caustic soda and the solution commonly known asviscose filtered to remove undissolved fibers and gel-like materials andripened to impart the desired properties for satisfactory spinning.

While highly refined wood pulps are advantageous in the viscose processfor the production of high grade yarns of superior strength and color,the reaction of the shredded alkali cellulose from such pulps withcarbon bisulfide is frequently incomplete. This impairment inthexanthating activity of the shredded alkali cellulose in the viscoseprocess may be due on the one hand to some damage to the fibers during,the shredding operation or on the other hand to incomplete comminutionof the alkali cellulose sheet or to formation of compressed fiberbundles. This difiiculty in efiecting satisfactory comminution of thealkali cellulose from highly refined pulp without damage is overcome, inour invention, by carrying out the operation with pulp treated with thepolyethenoxy alkyl ethers.

When the invention is practiced for effecting the hereinbeforementionedimprovements in shredding'in the viscoseprocess, certain furthereconomies are effected in the subsequent steps of xanthating, dissolvingand filtering. In viscose solutions there i usually a certain amount ofundissolved fibers and gel-like material due to the incomplete reactionof the cellulose with the carbon bisulfide during xanthation. Prior tospinning, the viscose solutions are filtered several times to removethese gels and undissolved fibers. In the event that the viscosesolutions, contain excessive amounts of undissolved and partiallydissolved fibers, filtration is an expensive operation. In such casesthe filters become rapidly clogged and the filter media must be changedfrequently in order that the viscose will pass through in a reasonabletime. Frequent changing of the filter medi is expensive, not only asregards consumption of filter cloth but also in I view .of the veryconsiderable amount of labor involved and also since a certain amount ofvisaccepts-- 9 T cosef lost every time. the filteriis opened up.Furthermore, when the viscose solutionscontain very large proportions ofgel-like materiaL'filtration is usually not altogether satisfactory inthat some of the smaller gel-like particles tend to pass through thepores of the cloth with adverse effect upon the spinning operation.

It has heretofore been the cose industry, when processing pulps whichtend to yield viscose solutions high in undissolved material and havingpoor filtration properties, to minimize such dimculties by carrying outthe xanthation with amounts of carbon bisulfide considerably in excessof that normally required. Use of excess carbon bisulfide is expensiveand in addition' is technically undesirable in that it may adverselyanect certain properties such as the ripening of the viscose and yarncharacteristics. We have found that when processing highly purifiedpulps which would normally tend to'give poorly filtering viscosesolutions, the addition of minute amounts of the polyethenoxy alkylethersuto the pulp so improves the shredding operation that the alkalicellulose subsequently reacts much more completely with carbon bisulfideand yields a viscose solution very free from undissolved and partiallydissolved cellulose particles and having good filtration properties.This result can be accomplished not only without the use of excesscarbon bisulfide, but in many cases satisfactory viscose solutions canbe obtained using amounts of carbon bisulfide very substantially lessthan the amounts normally required.

When the polyethenoxy alkyl ethers are incorporated in the wood pulp, bythe pulp manufacturer thereof, the pulp sheets come to the rayonmanufacturer in a form calculated to secure the full advantages of theinvention in the preparation and processing of the viscose into highgrade rayon yarns.

While it is our preferred practice to incorporate the polyethenoxy alkylethers in the drying on the machine of the wood pulp, preferably ahighly refined pulp containing not more than about 0.15% ofether-extractable material, for use in viscose the presence of thecompound in the pulp sheets may be secured in any other appropriatemanner. Moreover for use in viscose, the compound need not beincorporated in every sheet. It may also be added to only a portion orthe sheet as for example in strips on the pulp sheets. However, for usein acetylation it should be noted it is necessary to incorporate thepolyethenoxy alkyl ether prior to drying at elevated temperature and ina manner so that at least the surfaces of the pulp sheet are completelytreated.

The following small scale laboratory test may be conveniently used tocompare the reactivity of dry sheet pulp in the viscose process:

A bundle of 10" x 10" pulp sheets weighing approximately 650 gms. issteeped in caustic soda solution containing 18.5% NaOH and about 1.5%hemicellulose for 30 minutes at 30 C., and then pressed to a weight of2.70 times the original weight'of pulp.

The pressed sheets of alkali cellulose are shredded 60 minutes at 30 C.At the end of the shredding, the alkali cellulose is analyzed forpercent NaOH and percent cellulose, and the apparent density of thealkali cellulose is measured.

The shredded alkali cellulose is then placed in V gallon glass top fruitjars sealed with rubber rings andaged 24 to 48 hours at 3 C. underconditions predetermined to give viscose of about 35 seconds viscosity(time for practice in the vis- 10- fall 20 cm)" at the time it issubjected to testing.

The aged alkali cellulose is then xanthated in the glass Jars using 31%CS: based on cellulose in alkali cellulose and rotating the jars onrollers for minutes at 30 C. The xanthate is mixed with caustic soda andWater for minutes at 15 C. to give a viscose solution with composition8.5% cellulose and 5.25% NaOI-I.

After standing 24 hours at 20 C., a filtration test is made on theviscose. In this filtration test a plugging value is determined byfiltering through a standard cotton batting filter medium, taking ratemeasurement at increasing time increments.

The plugging value is calculated by extrapolation from thesemeasurements as the amount of viscose which would pass through one unitof filter area when the filter would be completely plugged. The higherthe plugging value the bet-- ter the viscose. Under the standardconditions of the test the plugging value therefore indicates therelative reactivity of the pulp sample proc essed.

A viscose-type wood pulp having an ether ex tract of 0.1 was tested bythe above procedure after treatment with a solution of a polyethenoxyalkyl ether. The samples and the test observations are shown in thefollowing Table II. The wood pulp sheets, dried on the manufacturingmachine, were later treated by spraying with a water solution of theagent named and redried at 10 0.

TABLE II Reactivity of viscose wood pulp treated with a polyethenomyalkyl ether Temperature of g ggf Plugging Treat Drying Cellulose Value01' Arter D 1; Viscose 'lreat ensl y r Untreated Control 0.149 440 1000. 148 410 100 0. 132 860 B-nonadecaethenoxy ether of oleyl alcohol.

. When viscose rayon is delustered by incorporatmg a suitable opacifyingagent in the spinning solution, usually an oil or a pigment such astitanium dioxide, it is necessary in order to get a uniformemulsifioation or dispersion of the agent throughout the body of .theviscose solution to use an emulsifying or dispersing agent. The treatedpulp of the invention produces viscose with exceptionally goodemulsifioation and dispersion properties which is quite remarkable inview of the small quantities of ethers used in the treatment of thepulp. The emulsifioation is characterized by the uniformity of size ofoil particles so that the resulting viscose solution is substantiallyfree from even small numbers of large oil globules which weaken thefilaments on spinning. The treated pulp therefore gives specialadvantages not only in regard to the reactivity in the viscose processbut also gives a viscose solution characterized by improved properties,as for example improved emulsifioation properties in the preparation ofdelustered rayon.

We claim:

1. As a new article of manufacture relatively dry refined wood pulp insheet form having incorporated therein from 0.02 to 0.50 percent byweight based on the bone dry weight of the pulp A steel ball t 7 of awater-soluble mixed ether containing a poly- 11 ethylene oxide radicaland an aliphatic hydrocarbon radical containing more than '7 carbonatoms.

2, An article of manufacture according to claim 1 in which the mixedether contains a polyethylene oxide radical with from 8 to 50 ethenoxyresidues and a normal primary aliphatic hydrocarbon radical with from 8to 20 carbon atoms.

3. In the preparation of mechanically compacted pulp sheets dried at anelevated temperature and formed of refined pulp relatively low in etherextractable matter, the improvement which comprises adding at a stageprior to completion of drying from 0.02 to 0.50 percent by weight basedon the bone dry weight of the pulp of a water-soluble mixed ethercontaining a polyethylene oxide radical and an aliphatic hydrocarbonradical containing more than 7 carbon atoms to minimize inactivation inproducing the treated sheets.

4. In the preparation of mechanically compacted pulp sheets dried at anelevated temperature and formed of refined pulp relatively low in etherextractable matter, the improvement which comprises adding at a stageprior to completion of drying from 0.02 tov 0.50 percent by weight basedupon the bone dry weight of the. cellulose of a mixed ether containing apolyethylene. oxide radical with 8 to 50 ethenoxy residues and a normalprimary aliphatic hydrocarbon radical containing from 8 to 20 carbonatoms tominimize.

inactivation in producing the treated sheets-l PAUL HENRY SCI-E O SSER.4 I

KENNETH n ssELL AY.

REFERENCES CITED The following referencesv file of this patent:

UNITED STATES PATENTS are. of record. in the

1. AS A NEW ARTICLE OF MANUFACTURE RELATIVELY FRY REFINED WOOD PULP INSHEET FORM HAVING INCORPORATIED THEREIN FROM 0.02 TO 0.50 PERCENT BYWEIGHT BASED ON THE BONE DRY WEIGHT OF THE PULP OF A WATER-SOLUBLE MIXEDETHER CONTAINING A POLYETHYLENE OXIDE RADICAL AND AN ALIPHATICHYDROCARBON RADICAL CONTAINING MORE THAN 7 CARBON ATOMS.